#include <iostream>
#include <stdio.h>

using namespace std;

int main() {
    double n;
    cin >> n;
    int n4 = 0;
    double n2=0;
    double n3=2;
    while(n2 < n){
        n2 += n3;
        n3 *= 0.98;
        n4 += 1;
    }
    cout << n4;
    return 0;
}